A semiconductor device includes a substrate with an active pattern, the active pattern having a first extension portion extending in a first direction substantially parallel to a top surface of the substrate, a second extension portion extending from a first end of the first extension portion in a third direction oriented obliquely to the first direction, a third extension portion extending from a second end of the first extension portion in a direction opposed to the third direction, a first projection portion protruding from the second extension portion in a direction opposed to the first direction, the first projection portion being spaced apart from the first extension portion, and a second projection portion protruding from the third extension portion in the first direction, the second projection portion being spaced apart from the first extension portion.